摇摆板颜色变化

Question

I am trying to launch multiple JFrames with a custom panel that I created called subpanel . [In case you are wondering about the naming, I have another class called masterpanel , which contains a button that launches a new frame containing a new instance of subpanel .

The purpose of the subpanel is that when the user hits the enter button, the color changes. Currently, I have each subpanel contain an inner class called EnterAction , which calls setBackground to change the color.

I was wondering how I can modify this so that I can synchronize the color change between all of my subpanels .

Currently, I have a variable green , which I believe I can pass between all of my panels. However, I'm not sure how I can get the EnterAction to change all of the currently active panels?

I was thinking of creating a list of active subpanels ? But will this cause an additional problem that I would need to maintain the list if the user closes a subpanel ?

Here is my code:

import java.awt.event.ActionEvent;
import javax.swing.AbstractAction;
import javax.swing.Action;
import javax.swing.KeyStroke;

public class SubPanel extends javax.swing.JPanel
{   
    private Action enterAction;

    public SubPanel() 
    {
        initComponents();
        enterAction = new EnterAction();

            //KeyBindings on the enter button
        this.getInputMap().put(KeyStroke.getKeyStroke( "ENTER" ), "doEnterAction");
        this.getActionMap().put( "doEnterAction", enterAction );
    }

    /**
     * This method is called from within the constructor to initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is always
     * regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        setForeground(new java.awt.Color(1, 1, 1));
        setToolTipText("");

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(this);
        this.setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 400, Short.MAX_VALUE)
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 300, Short.MAX_VALUE)
        );
    }// </editor-fold>                        
    // Variables declaration - do not modify                     
    // End of variables declaration                   

    private static int green = 240;

    private class EnterAction extends AbstractAction 
    {   
        @Override
        public void actionPerformed(ActionEvent ae) 
        {
            //System.out.println("Enter button is pressed");
            green -= 5;
            if (green <= 0) green = 0;
            setBackground(new java.awt.Color(255, green, 255));
        }
    }
}

EDIT: There's going to be a maximum of 5 panels. This eliminates the need to create a list maintain active panels.

Answer 1

Instead, create a PanelColorModel that holds the current color. Let interested panels register as a listener to this model, using one of the observer pattern implementations suggested here . Then your Action can update the model and listeners can react accordingly.

Answer 2

You can try to define a static Color attribute, so every time you hit Enter every subpanel will have the same color. Something like:

static Color subpanelBackgroundColor; //Every instance will have this.